Sony sa wct 290 wct291 ver 1 0

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SA-WCT290/WCT291 2 NOTES ON CHIP COMPONENT REPLACEMENT - Never reuse a disconnected chip component. - Notice that the minus side of a tantalum capacitor may be dam-aged by heat. SAFETY CHECK-OUT After correcting the original service problem, perform the follow- ing safety check before releasing the set to the customer: Check the antenna terminals, metal trim, metallized knobs, screws, and all other exposed metal parts for AC leakage. Check leakage as described below. LEAKAGE TEST The AC leakage from any exposed metal part to earth ground and from all exposed metal parts to any exposed metal part having a return to chassis, must not exceed 0.5 mA (500 microamperes.). Leakage current can be measured by any one of three methods. 1. A commercial leakage tester, such as the Simpson 229 or RCA WT-540A. Follow the manufacturers instructions to use these instruments. 2. A battery-operated AC milliammeter. The Data Precision 245 digital multimeter is suitable for this job. 3. Measuring the voltage drop across a resistor by means of a VOM or battery-operated AC voltmeter. The limit indication is 0.75 V, so analog meters must have an accurate low-voltage scale. The Simpson 250 and Sanwa SH-63Trd are examples of a passive VOM that is suitable. Nearly all battery operated digital multimeters that have a 2 V AC range are suitable. (See Fig. A) 1.5 kΩ 0.15 μF AC voltmeter (0.75 V) To Exposed Metal Parts on Set Earth Ground Fig. A. Using an AC voltmeter to check AC leakage. SAFETY-RELATED COMPONENT WARNING! COMPONENTS IDENTIFIED BY MARK 0 OR DOTTED LINE WITH MARK 0 ON THE SCHEMATIC DIAGRAMS AND IN THE PARTS LIST ARE CRITICAL TO SAFE OPERATION. REPLACE THESE COMPONENTS WITH SONY PARTS WHOSE PART NUMBERS APPEAR AS SHOWN IN THIS MANUAL OR IN SUPPLEMENTS PUBLISHED BY SONY. ATTENTION AU COMPOSANT AYANT RAPPORT À LA SÉCURITÉ! LES COMPOSANTS IDENTIFIÉS PAR UNE MARQUE 0 SUR LES DIAGRAMMES SCHÉMATIQUES ET LA LISTE DES PIÈCES SONT CRITIQUES POUR LA SÉCURITÉ DE FONC- TIONNEMENT. NE REMPLACER CES COMPOSANTS QUE PAR DES PIÈCES SONY DONT LES NUMÉROS SONT DON- NÉS DANS CE MANUEL OU DANS LES SUPPLÉMENTS PUBLIÉS PAR SONY. 1. SERVICING NOTES ............................................. 3 2. DISASSEMBLY 2-1. Disassembly Flow ........................................................... 6 2-2. SUB MAIN Section ........................................................ 6 2-3. SUB MAIN Board .......................................................... 7 2-4. Switching Regulator ....................................................... 8 2-5. SUB KEY Board, Bluetooth Module .............................. 8 2-6. SUB LED Board, Front Panel Assy ................................ 9 2-7. Loudspeaker (130mm)-203-11 ....................................... 10 3. TROUBLESHOOTING .......................................... 11 4. DIAGRAMS 4-1. Block Diagram - AMP/PANEL/ POWER SUPPLY Section - ............................................ 13 4-2. Printed Wiring Board - SUB MAIN Board (Component Side) - ....................... 15 4-3. Printed Wiring Board - SUB MAIN Board (Conductor Side) - ......................... 16 4-4. Printed Wiring Board - SUB KEY Board - ..................... 17 4-5. Schematic Diagram - SUB KEY Board -........................ 17 4-6. Printed Wiring Board - SUB LED Board - ..................... 18 4-7. Schematic Diagram - SUB LED Board - ........................ 18 5. EXPLODED VIEWS 5-1. Back Panel Section ......................................................... 19 5-2. SUB MAIN Section ........................................................ 20 5-3. Speaker Cabinet Section ................................................. 21 6. ELECTRICAL PARTS LIST .............................. 22 TABLE OF CONTENTS